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CAIE A-Level Biology 2.3 Proteins Question Bank

Practise protein questions by drawing amino acids, naming structure levels and using R-group interactions to explain haemoglobin or collagen function.

Syllabus
2028–2030
Course
Biology 9700
Level
AS

Exam points

  • draw amino acids or peptide bonds and link condensation or hydrolysis to water movement
  • assign primary, secondary, tertiary and quaternary structure from sequence or folding evidence
  • explain haemoglobin and collagen functions using haem groups, triple helices and R-group bonds

Covered syllabus points

2.3.1—Amino acids and peptide bonds2.3.2—Protein structure levels2.3.3—Interactions holding protein shape2.3.4—Globular proteins2.3.5—Fibrous proteins2.3.6—Haemoglobin quaternary structure2.3.7—Haemoglobin function2.3.8—Collagen structure2.3.9—Collagen structure and function

2.3 Proteins question 1

[Maximum number: 1]

Smooth muscle is a tissue composed of smooth muscle cells. The cells contain cytoplasm packed with proteins that are involved in contraction and relaxation.

Caldesmon is a large protein with a number of binding sites to attach to other proteins.

Caldesmon exists in two different forms, H-caldesmon and L-caldesmon.
H-caldesmon helps to regulate contraction and relaxation in smooth muscle cells.
L -caldesmon is found in some non-muscle cells, where it also acts as a regulatory protein.
- Caldesmon is coded for by a gene known as CALD1.
- CALD1 has 17 exons.
- The primary structure of H-caldesmon has a repeating sequence in the middle of the amino acid chain that is not present in L-caldesmon.

Suggest how the two different forms of caldesmon can still have similar functions, even though they have a different primary structure.

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